Alzheimer's disease is a progressive brain disorder that causes memory loss and cognitive decline. It has three main stages - early, middle, and late. The early stage involves short-term memory loss and difficulty concentrating. The middle stage brings more severe memory loss and inability to recognize family/friends. In the late stage, patients lose the ability to carry out daily activities. The Mini-Mental State Exam is used to screen for cognitive impairment, scoring from 0-30. Risk factors include age, family history, and genes. Caring for Alzheimer's patients focuses on safety, communication, and meeting basic needs.